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Plumbing Vents

I'm building an addition onto a home myself. It started as a 2,400 square foot total renovation / addition. Due to a change here and there, it has become a 4,200 square foot renovation / addition! I am having to do everything myself to keep costs low in order to even complete the project. Needless to say, I have to work into the wee hours of the night because I have a full time day job as well.

The home has 4 1/2 baths, a full kitchen, a second kitchenette, a laundry room and sinks in the basement and garage. It also has a wet bar area in another two areas.

I am trying to vent every single fixture as well as have the main drain stacks vented. All the vents will tie together in the attic. The sink vents are clear in all the diagrams I've seen however I'm held up because all the plumbing books I read mention that the vent line cannot run horizontal until at least 6" above the flood line of the fixture it is venting, which i'm not sure about when it comes to toilets and bath tubs.

I'm probably being over causious with my vents by adding too many, however I would rather be safe than sorry. My plan for the bath tubs and toilets is to add a vent pipe within the floor joints below the toilet and tubs, about 6" to 12" from the trap of the tub and about the same from the toilet 90 fitting each with a sanitary Y fitting . I want to then run the vent paralell to the drain pipe within the floor joists ane run it back up the wall behind the toilet and also near the tubs in the tub scenario and then run it up to the attic.

My confusion is that no diagrams ever show tubs or toilets vented individually, only through the main stack. I understand the concepts of x amount of feet from the main stack is okay to have something wet vented, etc, however like I said I want to be extra safe.

My question: Is there any code restriction against having a vent in the drain line beneath a toilet or tub running parralell to the drain line under the fixture and then up a wall? I would make certian the vent line intersects with the drain line at least 45 degrees or less from the top of the drain pipe, as the books state. I also understand you have to be a certain amount of distance away from the trap with the vent line tie in so you don't siphon water out of the trap when the line is draining.

Re: Plumbing Vents

Here is my best advice on this issue. I do most of my own plumbing in by five story apartment buidling build in 1912 but there are times that I do hire a professional plumber when I am not quite sure of myself. I do this because he has been around the block at least 1000 times on any issue that I have. By bringing in a professional plumber preferably someone on his own time for a few hours he knows the answers. It is a lot faster, cheaper and you have less time in research.

Re: Plumbing Vents

Thanks for your reply. I appreciate you taking the time to post it. I have a few friends who like me know "a little about alot", and the concensus is that you can't have a vent line running horizontal below a bath tub or toilet fixture tied into those fixtures drain lines. Most people are saying the vent line has to tie into the drain line and run straight up until at least 6" above the flood line of the fixture, at which point it could turn horizontal if needed. This apparently prevents any potential for fluid backup into the vent line that would have no way of being washed out, since the vents are dry.

It would probably be worth it to get someone out there and take a look.

Most of the toilets and tubs are within about 6 to 8' of the main 4" drain line which will have numerous vents tied into it, so I should (hopefully) be fine.

Thanks again for your post.

Take care.

Any other advice from anyone would still be well appreciated as I continue my seemingly never ending project......

Re: Plumbing Vents

It is ok to run your toilet and tub vents horizontil until going vertical in the wall. The code was written when using vent fittings as aposed to drainage fittings. You were not allowed to offset until 6" above flood level rim of the fixture, the vent is serving. If you offset due to structual reasons then you use drainage fittings. The new IRC code you only need one 2" vent per bathroom group. Hope this helps

Re: Plumbing Vents

Originally Posted by jca4591

Thanks for your reply. I appreciate you taking the time to post it. I have a few friends who like me know "a little about alot", and the concensus is that you can't have a vent line running horizontal below a bath tub or toilet fixture tied into those fixtures drain lines. Most people are saying the vent line has to tie into the drain line and run straight up until at least 6" above the flood line of the fixture, at which point it could turn horizontal if needed. This apparently prevents any potential for fluid backup into the vent line that would have no way of being washed out, since the vents are dry.

It would probably be worth it to get someone out there and take a look.

Most of the toilets and tubs are within about 6 to 8' of the main 4" drain line which will have numerous vents tied into it, so I should (hopefully) be fine.

Thanks again for your post.

Take care.

Any other advice from anyone would still be well appreciated as I continue my seemingly never ending project......

No offense -- getting in a professional plumber is the correct thing to do here. It seems you aren't quite clear how DWV works.
Vents originate from a vertical run ( which eventually runs out the roof ) -- they can run horizontal to within 6 inches above the flood level of the fixture they serve ( sink , tub ) --- the vertical run below the fixture is considered the drain and ties into the main or branch drain line.